1. Field of the Invention
The present invention relates to a video encoding method, a video encoder, and a Personal Video Recorder (PVR), and more particularly to a video encoding method and a video encoder which can effectively perform the conversion of the video encoding, and a Personal Video Recorder (PVR) capable of effectively displaying video signals.
2. Discussion of the Related Art
Recently, a variety of Personal Video Recorders (PVRs) capable of storing/reproducing digital broadcast streams have been developed and introduced to the market.
The PVR generally indicates all the hardware capable of storing digital video data, and includes a set-top box, a digital television set and so on.
The PVR stores a stream encoded with a Moving Picture Experts Group 2 (MPEG-2) format in a memory unit, and then reproduces the stored stream at a user-desired time. If required, some PVRs may encode an analog video signal according to an MPEG-2 format, and may store the encoded video signal in a memory unit.
FIG. 1 is a block diagram illustrating a conventional PVR.
Referring to FIG. 1, the conventional PVR includes an MPEG-2 decoder 11, a storage unit 13, and a display processor 14. If the PVR can encode the analog video signal, it can further include an MPEG-2 encoder 12.
The MPEG-2 decoder 11 decodes a received digital video signal, and outputs the decoded video signal. The display processor 14 can display the decoded video signal on a display screen. The decoded video signal is stored in the storage unit 13, and is then reproduced on the screen when a user desires to view the video signal.
If the MPEG-2 encoder 12 receives an analog video signal, it encodes the received analog video signal into a video signal of an MPEG-2 format, and stores the encoded video signal in the storage unit 13.
An MP@HL HD video image requires storage capacity of about 9 gigabytes to store an encoded MPEG-2 formatted bitstream of about 1 hour. An MP@HL SD video image requires storage capacity of about 2 gigabytes to store the encoded MPEG-2 formatted bitstream of about 1 hour.
Therefore, the conventional PVR has widely used a video encoder due to the increased production costs caused by the storage unit 13. In this case, the video encoder reduces a bit rate of the stored bitstream in consideration of the increased production costs caused by the storage unit 13, and performs a video-transcoding operation on the resultant bitstream.
The video encoder converts a compressed format of the decoded video signal using motion information and decoding-associated information into another format, and adjusts the scale of the motion information. The video encoder encodes the received video signal in the form of an MPEG-2 bitstream using the adjusted motion information, and creates an MPEG-2 formatted video signal having a low bit rate.
However, the above-mentioned video encoding apparatus and method for re-encoding the MPEG-2 format image using only the motion information of the adjusted scale, have disadvantages in that it may result inconsistent format of received image or deterioration of an image quality.
In the meantime, the H.264 (MPEG-4 Part 10/AVC) format is superior to the MPEG-2 format in light of compression rate- and image quality-aspects. Therefore, in order to reduce the image-quality deterioration encountered by the encoding of the MPEG-2 format image, an apparatus or method for transcoding the MPEG-2 format image into the H.264 format image has been developed.
However, the H.264 format image generally requires a large number of encoding calculations, which is higher than in the MPEG-2 format image by about 10 times, and also requires a large number of decoding calculations, which is higher than in the MPEG-2 format image by about 3 times, such that hardware performance for the H.264 format image must be superior to that of the MPEG-2 format image.
Therefore, provided that the PVR includes an encoder, which decodes the MPEG-2 format image using the MPEG-3 decoder and re-encodes the decoded image according to the H-264 format, it can prevent the image-quality deterioration from being generated, but it has a disadvantage that it requires a large number of calculations, a long calculation time, and a large amount of storage capacity.